1. Field of the Invention
The present invention relates to electrical pulse shaping, and more specifically, it relates to the combination of arbitrary amplitude high-speed pulses for precision pulse shaping to control the temporal profile of laser pulses.
2. Description of Related Art
Very short, high voltage electrical pulses are needed to control the temporal profile of laser pulses using Pockels cells in applications such as inertial confinement fusion. Pulse shaping is required in high energy pulsed lasers to compensate for gain saturation which distorts the output laser pulse . In addition, pulse shaping is desirable for improved target performance in fusion experiments. In the Nova Laser System at Lawrence Livermore National Laboratory (LLNL), the master oscillator pulse is modulated in time using a dual Pockels cell system which requires a shaped 4 kV pulse. While this works very well, the main disadvantage is that the shaping technique relies upon the reflection from non-uniform impedance transmission lines, which is not conducive to programmable control. Pulse shaping in this way began in the early 1980s using approximate models and experimental methods.
In the late 1980s, techniques were developed for systematic design of non-uniform transmission lines to obtain predetermined pulse shapes, but these methods were not computer controllable. A major change in master oscillator technology occurred with the Beamlet Laser System at LLNL, which used integrated optoelectronic modulators (EO modulators) to control the temporal pulse shape of the laser beam. These devices only require 8 volts to operate, opening up other possibilities for pulse shaping.
It is an object of the present invention to combine arbitrary amplitude high-speed pulses to achieve precision pulse shaping for control of the temporal profile of laser pulses.
A programmable pulse shape generator combines arbitrary high-speed electrical pulses for precision laser pulse shaping. The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them, delayed in time, on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates the light. The circuit can also be adapted to combine multiple channels of high speed data, multiplexing them into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect a 10xc3x97 increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through the equivalent of a super modem.
This pulse shaping module will be used to shape the electrical pulses which shape the laser pulse for the National Ignition Facility (NIF) at LLNL. It is currently being used there to shape pulses for the Beamlet laser. The invention can modulate light at 9 giga-samples per second (9 GS/s) without being optimized for higher speeds. This circuit topology can operate at speeds of 20 GS/s and beyond, to vastly increase the capability of short-haul fiber optic communication systems. In addition, it can be used in long-haul transmission systems to pre-shape the data pulse stream to compensate for path distortions (much like the path distortions experiences in Nova or NIF).